Reynoldsville is an unincorporated community in Union County, Illinois, United States. The community is along Illinois Route 3 and 146, just north of McClure and across the Mississippi River from Cape Girardeau, Missouri.

The unincorporated community has a major railroad passing through. A fishing lake, Lyerla Lake, is just to the east. Kornthal Church from 1852 is located in the community and Old Cape Road connects with Illinois Route 127.

• NACo